The pic is blurry, but looks like 18x²-21x-15 (3x-5)(6x+3) is the factored form. 3 and 6 are the factors of 18 -5, 3 or -3, 5 are the factors of -15 I line them up like this 3 -5 6 3 then I multiple them diagonally: 3*3=9, -5*6=-30, the sum of 9 and -30 is exactly -21, the coefficient for x. (If the sum doesn't make -21, I'd switch -5 and 3, or change to -3 and 5 to try again.) so the factored form is (3x-5)(6x+3)
Based on the graph shown, the intersection is (1.231, -0.452). 1.231 acts as coordinate x of the intersection, and -0.452 acts as coordinate y of the intersection.
In the equation the solution is the value of x. So the solution of the equation is the value of x. So, we use coordinate x of the intersection to find the solution of the equation, that is 1.231.